Erratum: Constraints on the Offspring Production Efficiency of Peromyscus and Other Rodents

Abstract

Limitations on the variability of features of the energy budget can importantly affect the evolution of reproductive fitness in organisms. Slobodkin & Dunn (1983) suggest that reproductive efficiency is constrained among species of Hydra. This paper shows that assimilation efficiency (AE) and the efficiency of converting maternal food into offspring during lactation (OPE) also vary little among five species of Peromyscus, and both are independent of body mass. The slight variation in gross OPE (including energy intake for female maintenance) that does exist is correlated with the amount of energy used for lactation relative to that used for maternal maintenance. Net OPE (excluding energy intake for female maintenance) is correlated with the relative energetic growth rate of the offspring (REGR). Net OPE also varies independently of body mass, but is correlated with REGR among 11 non-domestic rodent species in six genera (including Peromyscus). Although most of these rodents may be confined to a single 'economic' constraint system, Sigmodon hispidus (Say & Ord) clearly has an unusually high OPE, an innovation apparently made possible by the use of maternal body reserves and by weaning of offspring before they become fully endothermic, thus reducing offspring maintenance costs supported by the mother. The correlation between OPE and REGR also indicates a positive relationship between the speed and efficiency of offspring production, not a negative one as theorized. Key-words: Assimilation efficiency, energetics, evolutionary constraints, growth rate, lactation, Peromyscus, reproductive efficiency, rodents